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Both tracks, for 3790 and 3490, look very good and show no trace of problems. I can't see any reason for concern about accuracy. Maybe one should find worst conditions for signal reception to observe differences.

Both tracks, for 3790 and 3490, look very good and show no trace of problems. I can't see any reason for concern about accuracy. Maybe one should find worst conditions for signal reception to observe differences.

Hi,

I disagree with you when said "I can't see any reason for concern about accuracy."
In my opinion is necessary the same test but inside big cities (downtowns) with tall buildings.

I can not believe that is not reason about accuracy.
I think my eyes is not lying to me when my converted 3790/34XX put my car icon above the houses and buildings on GPS map during the same route that I use every day.
In converted unit appears almost 90% of the time this issue.
Look, this not occurs when using original 3790 firmware.

I think that is necessary more outdoor tests like this but inside big cities.

The problem to me is that I can not do this kind of test because I don't have 2 Nuvis 3790.

@Caty
I'm guessing that the grey line is 3590 and the green is 3490 with kunix's flash then. Interesting as a side-observation is that the 3790 [red] seems to be more consistent than the 3590 [grey] if that's that case.
@all
It would be worthwhile to test 3790 against 3490 in adverse 'city canyon' conditions so i'll do a side-by with those 2 in the big smoke when i can. The area used yesterday has quite big trees in places but there's nothing quite like the satellite signal blocking effect of tall buildings, is there? I really don't want to venture into the city with 4 devices strapped to the windscreen though. I attracted some unwanted hard looks from Sunday afternoon power walkers and joggers while driving aimlessly around in their leafy suburb and i'm sure more than one of them noted down my plate number 'just in case' after i had passed them several times. I didn't quite look like this, but it felt like it:

Maybe i'll reconvert the 3490_kunix later to conventional fw 3490 and add it in as well.

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The great material produced by Neil can be analyzed from different perspectives, or more objectively, under various zoom levels, which can result conclusions somewhat different from those shown above. Our comrade Kanupus seems analyzed these data with a zoom farthest and concluded that "Both tracks, for 3790 and 3490, look very good and show the trace of problems. I can not see any reason for concern about accuracy .. ". I, on the other hand, used a zoom closest of the tracks taking the cue Caty's, working over Google Earth images which allows a realistic view of the terrain. Based solely on these observations I have come to some conclusions:

The first and unquestionable conclusion is about the 3790 real, which confirmed being in fact very accurate, despite the "evil tongues" lol, because your tracklog remained almost 100% of the path correctly positioned on the roads, an excellent device! As I currently have a 3490 new, soon I will make a comparison with the 3790 real, but I believe it must be equivalent in terms of accuracy.

Neil’s test also made it clear that the converted 3490 is far less precise than the 3790 real, as shown in the screens below attached of Google Earth. So if it can be concluded that without doubt the accuracy in gps screen is linked to the tracklog recorded and is not mere "impression" or mistake of uninformed users. The lowest precision shown on the screen of 3790 converted implies greater quantities of positioning errors on the ground, as shown by the tracklogs. The real 3790 was really accurate, the real 3590 not so much, the 3790 converted have substantial failures during the path, as shown in the attached images, and the 3790 Kunix 's, a case that I'll comment the part. I was careful to follow the tracklogs with extended zoom from the beginning to the end of the paths and captured many images of inaccuracy of 3790 converted, but for practicality I am publishing only a few. To make it easier I have attached the kml files for viewing in Google Earth for those interested. It is good to remember that accuracy in screen is not an absolute datum, but an order of magnitude, and not necessarily instant information. It may take some time for the system to change the accuracy shown on the screen, for example if you have a 3 meters brand in the sky opened and go into place without or with low signal It may take some time to appear on the screen the new "precision".

In relation to "notable" inaccuracy of 3790 converted with Kunix firmware, what seems to be a huge disappointment, I think we can see optimistically. That's because somehow the Kunix changed something in a region that has a direct relation with the accuracy of gps, it now remains to find out exactly which. Such inaccuracy also proved more than evident that the firmware, or part of it, is directly related to the positioning accuracy.

All these tests and analysis was an apprenticeship: really the best way to compare the accuracy is analyzing tracklogs of several gps, preferably on a reliable bases, in many cases of urban perimeters, with satellites photos as Google Earth (maps may be more susceptible to errors), since equality criteria are followed in the measurements, as previously mentioned. Also important to note that many of the errors presented are corrected, or rather, masked, by the Lock on Road of gps, so that most users do not give much importance to "accuracy" of 3790 converted. Anyway, it would be interesting to also do tests with lock on Road enable, because the inaccuracy can fix the vehicle in other streets and other aberrations, as I've seen it happen several times. The resulting tracklog would be funny..

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Here is real 3490 walking log for Google Earth and Mapsource.
It seems to match the 3m accuracy of the 3490, A bit shaky for my liking, Ignore the first few point as the unit was still acquiring sats.(finding it's feet)
This was my lunch time walk today shared with a Large Ice Cold Coke.

Last edited by dasilvarsa; 6th May 2013 at 18:34.

The difference between stupidity and genius is that genius has its limits.
Albert Einstein.

Just short question - as you may remember I have 3790->3490 transformed many times forward and backward.
I think to do the following - to erase totally all info using RMP.
Then to restore to original 3790 and then to participate in the tests.
The question is - did that will give me "virgin" 3790 or it will be under question? What more can I do to get "virgin" unit if RMP is not enough?
Sorry to join the team so late, but we have very long holidays because of orthodox Easter.
I can compare my results with 2595 which has same accuracy as 3490. Is it OK?

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